Hepatitis C virus (HCV) continues to be a global epidemic. In most cases, HCV infection becomes chronic and can persist for decades, leading to cirrhosis, end-stage liver disease and hepatocellular carcinoma. Currently, 2% of the human population—approximately 123 million people—is infected with HCV. In fact, there are 3-4 times more individuals infected with HCV than HIV, making virus transmission a major public health concern. In the United States, HCV infection is the most common cause of liver transplantation and results in 10,000 to 20,000 deaths a year. There is no vaccine, and current HCV therapy, pegylated interferon-alpha in combination with ribavirin, leads to a sustained response in only 50% of genotype 1-infected patients, the prevalent genotype in the United States. The current HCV treatment stimulates the patient's immune system to clear the virus, but numerous side effects cause many patients to prematurely stop treatment. Two new protease inhibitors now used to improve treatment outcomes do not eliminate the need for interferon-alpha and ribavirin. Given the high prevalence of infection and poor response rate, inhibitors that specifically target HCV proteins with fewer side effects are desperately needed. In addition, an effective vaccine would greatly reduce the spread of the virus.
International Patent Publication No. WO 2008/022401 to Mc Caffrey, et. al, describes preparing an HCV E2 polypeptide having internal deletions of the regions within E2. However, this reference does not describe a stable cell line that expresses E2. The cells perform transient expression, which is only good for a few days. The E2 DNA is not incorporated into the genome of the cell and after several days, the cells will remove the gene. This method is inefficient. This publication also does not utilize a construct containing an Fc or protein-A tags.
U.S. Pat. No. 6,326,171 to Chiron describes preparing an HCV E2 polypeptide involving a specific region of E2 that ends at amino acid 715. The construct used does not contain a tag. The cells used for expression are non-human, and included BSC40 (African Green monkey) and F503 (chimpanzee fibroblasts).
U.S. Pat. No. 6,020,122 to Abbott Laboratories describes preparing an HCV E2 polypeptide without the use of a tag. The cells used for expression are CHO (Chinese Hampster Ovary) cells.
However, there still exists a need in the art for more efficient methods of preparing HCV E2 polypeptides, expression of higher levels and higher quality HCV E2 polypeptides, HCV vaccines and inhibitors of HCV infection.